What is the importance of electronegativity?

1. Electronegativity can be used to predict the nature of bonds between two atoms.
(i) If the two atoms are identical and have high electronegativity then the bond between them is called non-polar covalent bond or purely covalent bond. For example, H₂ (or H-H), Cl₂ (or Cl - Cl).
(ii) If the two atoms are dissimilar and have high electronegativity, then the bond between them is called a polar covalent bond. For example H -Br. Li—Cl etc.

2. Electronegativity helps us in predicting the polarity of covalent bonds.
(i) The greater the electronegativity difference between the two bonded atoms, the greater is the polarity of the covalent bond. For example, a bond between H and Cl is more polar (electronegativity difference = 0.9) than the bond between Br and CI (electronegativity difference = 0.2).

(ii) If the two atoms are dissimilar and have a large difference in their electronegativity,then the bond between them is called an electrovalent bond (or ionic bond).